This article presents an efficient method for the synthesis of 3,5-dinitrosalicyl hydrazide-15N2, with salicylic acid as the common substrate. Nitration of salicylic acid with KNO3-15N provided 3,5-dinitrosalicylic acid-15N2 and then we got 3,5-dinitrosalicyl hydrazide-15N2 by the esterification and hydrazinolysis reaction. The yield of 3,5-dinitrosalicyl hydrazide-15N2 was 55.5% based on K15NO3. The product was confirmed by NMR and LC-MS to be the target compound. Its chemical purity was 97.3% and isotopic enrichment of 15N was 99. 2 atom%15N. It could be used as internal standard in the field of food safety testing．